JP2021508129A - Pulse gas supply method and equipment using a shutoff valve - Google Patents

Abstract

The present invention is a fluid control system used for supplying fluid pulses, and includes a flow channel, a shutoff valve for starting and ending a fluid pulse from the flow channel, and a mass flow controller (MFC). .. This MFC controls switching between a control valve that controls the flow of fluid in the flow channel, a flow sensor that measures the flow rate in the flow channel, and a flow rate of the fluid passing through the control valve and a shutoff valve, and controls the switching of the fluid pulse. It is equipped with a controller that controls the mass of the fluid supplied between them. Control of the flow of fluid through the control valve can be based on feedback from the flow sensor during the pulses started and terminated by the shutoff valve. [Selection diagram] Fig. 6

Description

Related application

This application is a continuation of US Patent Application No. 15 / 887,447 filed on February 2, 2018, and the entire teachings thereof are cited as part of this application by reference.

A mass flow controller (MFC) is a device that measures and controls the flow of liquids and gases. Generally, an MFC includes an inlet, a discharge port, a mass flow sensor, and a proportional control valve that is regulated to obtain the desired mass flow.

In semiconductor manufacturing processes, such as atomic layer deposition (ALD) processes, a variety of different gases and gas mixtures are supplied in varying amounts over several processing steps. Normally, the gas is stored in a tank of a processing facility, and a gas measuring system is used to supply the measured gas from the tank to a processing apparatus (chemical vapor deposition reactor, vacuum sputtering apparatus, plasma etching apparatus, etc.). Typically, components such as valves, pressure controllers, mass flow controllers (MFCs), and mass flow ratio control systems are provided in the gas metering system or in the flow path from the gas metering system to the processing equipment.

A pulse gas supply device has been developed to supply a pulsed gas mass flow to a semiconductor processing instrument. In high-speed processes, pulsed gas feeds can be used to make advanced three-dimensional integrated circuits with silicon penetration vias (TSVs) that provide interconnects between dies and wafers.

The fluid control system used for the pulse supply of the fluid includes a flow channel (flow path), a shutoff valve for starting and ending the pulse of the fluid from the flow channel, and a pulse mass flow controller (MFC). The MFC controls switching between a control valve that controls the flow (flow) of the fluid in the flow channel, a flow sensor that measures the flow rate in the flow channel, the flow of the fluid that passes through the control valve, and the shutoff valve. A controller that controls the mass of the fluid supplied during the pulse of the fluid is provided.

The MFC may be a pressure type MFC or a thermal type MFC. The control valve is preferably a proportional valve that generates a flow output proportional to the control input (for example, an electronic control input from the controller). Proportional control valves can be used to control the level of fluid flow.

The controller can control the flow of the fluid through the control valve based on feedback from the flow sensor during the pulses started and terminated by the shutoff valve.

The flow sensor may include a control fluid (throttle) arranged between the control valve and the shutoff valve in the flow channel. The flow sensor further comprises an upstream pressure sensor configured to detect an upstream pressure at an upstream position between the control valve and the control fluid in the flow channel and said in the flow channel. It may be provided with a downstream pressure sensor configured to detect the downstream pressure at a downstream position between the fluid control and the shutoff valve. The flow sensor configured in this way measures the flow rate based on the upstream pressure and the downstream pressure.

The controller is a function of i) the measured flow rate, ii) the detected pressure, iii) the start time (start time) of the fluid pulse, and iv) the end time (end time) of the fluid pulse. May be configured to determine the estimated number of moles of fluid supplied. The controller may be further configured to control the flow through the control valve and the switching of the shutoff valve based on the estimated number of moles of the supplied fluid.

The controller may be configured to determine the estimated number of moles of the supplied fluid based on the determination of the residual flow rate and the measured flow rate. The controller receives the upstream pressure signal corresponding to the upstream pressure and the downstream pressure signal corresponding to the downstream pressure, and i) the downstream pressure and ii) the control fluid and the shutoff valve. It may be configured to determine the residual flow rate as a function of the dead volume between.

The controller may be configured to switch (eg, close) the shutoff valve based on a calculation of the mass of the fluid supplied during the pulse of the fluid. In particular, the controller may be configured to determine the estimated number of moles of the supplied fluid by the following equation.

In the equation, Δn is the estimated number of moles, Q _m is the flow rate measured by the flow sensor, V _d2 is the dead volume between the control fluid and the shutoff valve, and P _d is. The downstream pressure, t ₁ is the start time of the pulse, and t ₂ is the end time of the pulse.

The flow rate can be measured as a function of the upstream pressure, the downstream pressure, and one or more properties of the fluid (such as molecular weight MW or specific heat ratio γ).

The system may further include a temperature sensor configured to measure the temperature of the fluid in the flow channel, in which case the flow rate is further measured as a function of the temperature of the fluid. be able to.

The controller is configured to receive a control signal from the host controller, which is the identification of the fluid, the desired number of moles of the pulse of the fluid, the duration of the pulse of the fluid, and the repetition of the pulse. It may include a number.

The shutoff valve may be integrated with the pulse MFC or may be provided outside the pulse MFC. For example, the external shutoff valve may be a three-way valve connected to the processing chamber and discharge line. The system may include a plurality of external shutoff valves. One of the shutoff valves may be connected to the processing chamber and the other one of the shutoff valves may be connected to the discharge line.

The method of supplying the fluid pulse is to control the flow of the fluid to the flow channel by using a control valve, to measure the flow rate in the flow channel by using a flow sensor, and to control the switching of the shutoff valve. The fluid supplied during the pulse of the fluid by controlling the start and end of the pulse of the fluid from the flow channel, the flow of the fluid passing through the control valve, and the switching of the shutoff valve. Including controlling the mass of.

Control of the flow of the fluid through the control valve can be performed based on feedback (eg, feedback from the flow sensor) during the pulses started and terminated by the shutoff valve.

The method further comprises detecting an upstream pressure in the flow channel at an upstream position between the control fluid arranged between the control valve and the shutoff valve and the control valve, and the flow channel. Within, it may include detecting a downstream pressure at a downstream position between the control fluid and the shutoff valve. The measurement of the flow rate in the flow channel can be performed based on the upstream pressure and the downstream pressure.

The method further comprises a fluid supplied as a function of i) the measured flow rate, ii) the measured pressure, iii) the pulse start time of the fluid, and iv) the end time of the fluid pulse. It may include determining the estimated number of moles of. The flow of the fluid through the control valve and the switching of the shutoff valve can be controlled based on the estimated number of moles of the supplied fluid.

Embodiments of the present invention have several advantages. By providing a shutoff valve controlled by an MFC (eg, a controller based on the estimated number of moles of gas supplied), in embodiments, the pulse gas supply is accelerated, the accuracy of the pulse gas supply is improved, and the desired pulse shape is obtained. It can be adapted, simplifying pulse gas supply, saving gas usage, minimizing gas species cross-contamination in the chamber, and eliminating the problem of MFC control valve leaks. An embodiment of the present invention can provide a comprehensive solution for high-speed pulse supply applications (ALD process, TSV process, etc.) using a mass flow controller.

The above content becomes apparent from the following more specific embodiments of the exemplary embodiments shown in the accompanying drawings. In the accompanying drawings, the same reference numerals in the drawings indicate the same parts. These drawings are not necessarily scaled and are emphasized in illustrating the embodiments.
It is a figure of the conventional pulse gas supply system using a thermal mass flow controller (MFC) and a diversion line. It is a figure of the conventional pulse gas supply system which adopted the high-speed responsive MFC. It is another figure of the conventional pulse gas supply system which adopted the high-speed responsive MFC. It is a figure of the conventional pulse gas supply system using the attenuation rate pulse supply. It is another figure of the conventional pulse gas supply system using the attenuation rate pulse supply. It is a figure of the pulse supply using the gas dose determined by the product of the flow setting point (Q) and the supply time (Δt). It is a schematic diagram of the conventional pressure type pulse MFC apparatus. It is a schematic diagram of the pressure type pulse MFC which has an integrated shutoff valve. It is a graph which shows the pulse shape of the gas pulse supplied by using the MFC which is not provided with the integrated shutoff valve. FIG. 5 is a graph showing the pulse shape of a gas pulse supplied using an MFC having an integrated high-speed responsive shutoff valve. FIG. 5 is a diagram of an exemplary pulsed MFC system with an external shutoff valve. FIG. 5 is a diagram of an exemplary pulsed MFC system with an external shutoff valve and discharge line. FIG. 5 is a diagram of an exemplary pulsed MFC system with two external shutoff valves and a discharge line.

An exemplary embodiment will be described below.

A fluid control system used for pulse feeding of a fluid such as a process gas in a semiconductor manufacturing process or a chemical process is provided. The fluid control system includes a mass flow controller (MFC) and a shutoff valve that initiates and terminates one or more pulses of fluid from the flow channel.

In an industrial process, it may be necessary to supply a desired number of moles of fluid while a pulse of fluid is being supplied to the processing chamber.

"Mole" is a unit of measurement used for the amount of substance in the International System of Units (SI) (the unit symbol is mol). A "mol" is a number of constituent particles (eg, atoms, molecules, ions, electrons, etc.) equal to the number of atoms present in 12 g of carbon-12 (12C: by definition, an isotope of carbon with a standard atomic weight of 12). Or as an amount of substance containing photons) or as a sample. This number is indicated by the Avogadro constant (value is about 6.022140857 × 10 ²³ mol ^-1 ). Mols are widely used as a convenient way to represent the amount of reactants and products in a chemical reaction. Molar volume (symbol: V _m ) is the volume occupied by 1 molar substance at a given temperature and pressure. The molar volume is equal to the molar mass (M) divided by the mass density (ρ).

Conventional approaches to pulse gas supply include switching the gas flow on and off in the MFC by the host controller. Another conventional approach is to measure the volumetric pressure to deliver a pulse using the fill volume and discharge volume. The disadvantage of these conventionally known approaches is that they impose a high workload on the host controller, which must calculate and adjust the flow rate to deliver the required amount of gas. As the pulse width becomes shorter, the communication jitter between the host controller and the MFC reduces the pulse gas supply performance in terms of repeatability and accuracy. Conventional pulsed MFCs (particularly pressure pulsed MFCs) are not ideal in pulse shape and tend to have long tails (see, eg, FIG. 7A and related description).

FIG. 1 shows a conventional pulse gas supply system 100 using a thermal mass flow controller (MFC) 110, a host controller 120, and a three-way valve 130 connected to a shunt line and a processing chamber. The host controller 120 gives an instruction to the MFC 110 to supply a constant flow rate of gas from the gas source, activates the three-way valve 130, and switches the flow to the processing chamber or the diversion line based on the desired pulse duration. The system 100 does not use feedback on the amount of gas actually supplied to the processing chamber. The disadvantage of a pulse gas supply system such as System 100 is that the accuracy and repeatability of the pulse depends on the shutoff valve (eg, the three-way valve 130). Further, the MFC of such a system constantly flows gas and wastes the process gas through the diversion line, which is not desirable because the process gas may be expensive.

FIG. 2A shows a conventional pulse gas supply system 200 that employs a fast responsive thermal MFC 210 such as a thermal MFC based on microelectromechanical system (MEMS) technology. The host controller 220 directly controls the pulse supply using standard flow control. The standard flow control mode is
a) A processing step in which the host controller transmits a flow setting point Q at a desired pulse start time (t _{1) in order to start the flow.}
b) A processing step in which the host controller sends a zero (“0”) flow set point at the desired end time (t _{2) to end the flow.}
c) It may include a processing step of repeating the above steps "n" times in order to obtain a desired number of pulses from the _{time (t 3).}

FIG. 2B is a graph showing an example of a desired flow rate (“setting point”) and an actual flow rate (“flow”) when the system 200 of FIG. 2A is used in the standard speed control mode.

The conventional approaches shown in FIGS. 2A-2B have some drawbacks. Although the MFC provides high speed control (eg, <500 msec), it may not be fast enough for the requirements of a particular ALD and TSV process. Further, although the MFC operates according to the set point, it does not adjust the initial gas lamp up to the set point. The supply is based only on time and there is no feedback on the amount of gas actually supplied. In addition, the digital communication "jitter" between the host controller 220 and the MFC 210 can affect the repeatability of the pulse supply. In addition, although thermal MFCs based on MEMS technology are fast, they may not be compatible with corrosive gases.

FIG. 3A shows a conventional pulse gas supply device 300 using a pressure type pulse gas supply. A pressure-based molar measurement technique is known in the art, which provides a pressure (P) response of 305 to time (t) for a gas introduced into a known volume, as shown in FIG. 3B. Use. The device 300 includes a chamber 350 having a known volume, a _{valve 340 located on the upstream side (“V in} ”) of the chamber 350, and a valve 345 located _{on the downstream side (“V out”) of the chamber 350.} .. Further, the chamber 350 is provided with a pressure sensor 365 and a temperature sensor 360.

First, the apparatus 300 may be filled by opening the valve 340 on the upstream side and closing the valve 345 on the downstream side, whereby a certain period (“filling” period Δt = (t ₁ −t ₀ )),. Figure 3B) gas stream (Q _i) to flow into the device over filled chamber 350, can cause a change in pressure. At time _{t 1} and the pressure _{P 2,} the valve 340 on the upstream side is closed ( _{"V in} closed"). _{The process then has a period (t 2-} t ₁ ) during which the gas in the chamber 350 can be stabilized at the set point. During this period, pressure and temperature measurements are taken, for example, by the pressure sensor 365 and the temperature sensor 360. When opening the downstream side of the valve 345 ( _{"V out} opening" time _{t 2,} Fig. 3B), until the valve 345 is closed again ( _{"V out} closure" of time _{t 4),} the gas flow _{(Q o)} is It flows out of the device 300 and supplies a pulse of gas from the device to the processing instrument over a period of time (“supply” period Δt = t _4- t ₂ ) and pressure change (ΔP = P ₁ −P _2).

Pressure-based molar measurement methods and devices are further described in Ding's US Patent Application No. 13 / 626,432 (published March 27, 2014 as US Patent Application Publication No. 2014/0083514). The entire contents of this document are cited by reference as forming part of this application. Multi-channel pulse gas supply with a flow rate determined based on the pressure drop in the supply chamber is described in US Pat. No. 9,348,339 by Ding et al., Issued May 24, 2016. There is. The entire contents of this document are cited by reference as forming part of this application.

The pulsed gas supply shown in FIG. 3B can be implemented by a program on the controller of device 300 that executes the supply recipe. The pulse supply is started by a trigger signal (for example, a control signal from the host controller). The supplied gas can be estimated based on the ideal gas law Δn = (ΔP * V) / (R * T).

The approaches shown in FIGS. 3A-3B have some limitations. The accuracy and repeatability of the pulse supply depends on the speed and reliability of the shutoff valve on the downstream side. A shutoff valve with a short response time is desired. However, as the valve ages, adaptive adjustments may be required to increase complexity, or the valve may need to be replaced, which usually requires process interruption. In many cases, the pulse shape (eg, pulse width) is not what you want, or the desired square wave and pulse do not match well. Further, it takes time because the chamber 350 needs to be filled with a certain amount of gas. The time of the rapid gas supply cycle is limited by the gas filling time and stabilization time before each pulse.

On the other hand, the advantage of the pressure-type molar measurement technique is that these techniques can be applied without requiring information about a specific gas or gas mixture to be measured. The gas flow rate derived by applying the mass balance to the chamber volume and the law of ideal gas is not gas-dependent and is the three state variables that characterize the behavior of the gas to be measured: pressure (P) and temperature. Based on (T) and volume (V).

FIG. 4 shows pulse feeding with a gas dose determined by the product of an ideal rectangular flow setting point (Q) and feeding time (Δt). The gas supply cycle 400 includes a "pulse on" period (t _2- t ₁ ), a "pulse off" period (t _3- t ₂ ), a gas dose (eg, the number of moles of gas per pulse), and It can be specified by the number of pulses per cycle. For pulse supply, the molar supply of gas can be defined as the ideal flow setting point (Q) x supply time (Δt = t ₂ −t _1).

Although the flow supply of the step function as shown in FIG. 4 is ideal, it is not realistic due to the time constants of the actual sensor and valve. For practical applications, dose accuracy and repeatability in the required time frame are important objectives. Therefore, it is desirable to supply the gas with accuracy and repeatability. For this purpose, the required amount of gas can be supplied within a specified time by calculating and adjusting the flow rate using the calculation function of the MFC. In particular, the MFC can be configured to calculate the gas dose actually supplied and adjust to the target pulse gas dose.

FIG. 5 shows a conventional system 500 used for pulse supply of gas. The system 500 has a pressure MFC 510 configured for pulse feeding. The host controller 520 communicates with the MFC 510 to provide the MFC 510 with information about desired pulse supply information such as, for example, pulse molar set points, pulse on periods, pulse off periods, and pulse repeat counts. To initiate the pulse supply cycle, the host controller 520 sends a trigger signal to the MFC 510. The MFC 510 has a control valve 580 (eg, a proportional control valve) that controls the flow of fluid from the gas source to the flow channel 515. The controller 505 of the MFC 510 is configured to control the flow of fluid through the control valve 580 to control the fluid supplied to the processing chamber during the pulse of the fluid. The controller 505 controls the flow of the fluid passing through the control valve 580 based on the feedback from the flow sensor 525 provided to measure the flow rate (Q) in the flow channel. The flow sensor 525 includes a fluid control fluid 570 on the downstream side of the upstream pressure sensor 555 and on the upstream side of the downstream pressure sensor 565 in the flow channel 515. The control valve 580 is located upstream of the control fluid 570 and these pressure sensors.

The pulse gas supply amount in the device of FIG. 5 is calculated by the following formula.

In the equation, Δn is the number of moles of supplied gas, Q is the flow rate measured by the flow sensor, t ₁ is the pulse start time, and t ₂ is the pulse end time.

The pressure-type pulsed MFC gas delivery is further described in International Publication No. 2012/116281 (Title: "System for and Method of Fast Pulse Gas Delivery") by Junhua Ding et al. The entire contents of this document are cited by reference as forming part of this application.

FIG. 7A shows a graph of pulse supply using the system 500 of FIG. The flow rate is shown as a function of time when the actual pulse shape 704 is superimposed on the ideal pulse shape 702. The pulse width of the ideal pulse is 300 ms. The area below the curve represents the number of moles of gas supplied. In the actually supplied pulse, the transient response (eg, tail) is large, which may be due to the volume between the sensor (eg, downstream pressure sensor 565) and the control valve 580. When the control valve 580 is closed to terminate the pulse, the gas in the flow channel 515 continues to flow into the processing chamber.

Transient flow may not be very important if the pulse is delivered over a relatively long period of time. On the other hand, if the pulse is short, transient flow can be a problem. Normally, the MFC is calibrated in a steady state. However, the transient response of the MFC control valve may vary from valve to valve.

FIG. 6 shows an improved fluid supply system 600 used for pulse supply of fluid according to an embodiment of the present invention. The system 600 comprises a pressure pulse MFC 610 with an integrated shutoff valve 690. The MFC 610 has a control valve 680 (eg, a proportional control valve) that controls the flow of fluid in the flow channel 615. The shutoff valve 690 is configured to start and stop the pulse of fluid from the flow channel 615, for example to the processing chamber. The pulse MFC controller 605 is configured to control the flow of fluid through the control valve 680 and the switching of the shutoff valve 690 to control the mass of fluid supplied during the pulse of the fluid. The controller 605 can control the flow of fluid through the control valve 680 based on the feedback from the flow sensor 625 during the pulses started and terminated by the shutoff valve 690.

In FIG. 6, the control valve 680 is shown in front of the flow sensor 625 to control the flow to the flow channel 615, but the control valve can also be placed after the flow sensor.

The flow sensor 625 is provided to measure the flow rate (Q) in the flow channel 615. In the embodiment shown in FIG. 6, the flow sensor 625 comprises a control fluid 670 disposed between the control valve 680 and the shutoff valve 690 in the flow channel 615. The flow sensor 625 further includes an upstream pressure sensor 655 and a downstream pressure sensor 665. The upstream pressure sensor 655 is configured to detect the _{upstream pressure (Pu} ) at the upstream position between the control valve 680 and the control fluid 670 in the flow channel 615. The downstream pressure sensor 665 is configured to detect the _{downstream pressure (P d} ) at the downstream position between the fluid control fluid 670 and the shutoff valve 690 in the flow channel 615. As is known in the art, the flow sensor is configured to measure the flow rate based on the upstream pressure and the downstream pressure. The system may further include a temperature sensor 660 configured to measure the temperature of the fluid in the flow channel 615, in which case the flow rate is further known in the art. In addition, it can be measured as a function of the temperature of the fluid.

As shown in FIG. 6, the pulse MFC controller 605 communicates with the host controller 620 to send and receive data about the fluid supply process. The controller 605 may be configured to receive a control signal from the host controller 620, for example, to identify parameters used to pulse the fluid. The control signals include fluid identification, the desired number of moles of fluid pulses, the desired duration of fluid pulses, the off time between pulses, and the number of pulses. The controller 605 may be configured to control the flow through the control valve 680 and the switching of the shutoff valve 690 based on the estimated number of moles of fluid supplied. The controller 605 is configured to adjust the flow setting point of the control valve 680 to control the flow passing through the valve during pulse supply. Controller 605 may also be configured to control the flow set point and pulse duration (eg, the actual pulse-on period) during pulse supply based on the estimated number of moles supplied. .. In one embodiment, the controller estimates the molar amount of fluid supplied as a function of i) measured flow rate, ii) residual flow rate, iii) fluid pulse start time, and iv) fluid pulse end time. Determine the number. Controller 605, an upstream pressure signal corresponding to the upstream pressure (P _u), to receive a downstream pressure signal corresponding to the downstream pressure (P _{d), i)} and the downstream pressure and ii) system fluid It is configured to determine the residual flow rate as a function of the dead volume with the shutoff valve.

In the system shown in FIG. 6, a high-speed responsive shutoff valve 690 is added to the pressure pulse MFC610 in order to obtain a more rectangular or near-ideal pulse shape. If not shut off, the reduced flow over a long period of time tends to adversely affect the pulse shape and supply accuracy after the control valve is closed. Further, since the supply speed is improved by using the shutoff valve 690, the system 600 can supply a pulse for a short time (100 to 200 ms). Since the control valve 680 and the shutoff valve 690 can be closed at the same time at the end of the pulse, no fluid leaks into the processing chamber.

In the embodiment shown in FIG. 6, a shutoff valve 690 integrated with the pulse MFC610 is provided. The shutoff valve may be mounted on the outside of the pulsed MFC, including the thermal MFC, as shown in FIGS. 8-10. Such a solution is compatible with existing pulse MFCs such as the MKS P9B MFC (MKS Instruments, Inc.), which has a pulse gas supply function.

When an external shutoff valve is used, a discharge line (eg, a diversion line) may be used to ensure that the pulse MFC has a deterministic initial condition for each pulse supply, as shown in FIGS. 9-10. This discharge line allows the fluid to be purged from the flow channel before the start of the pulse.

Embodiments of the present invention are extensions to existing pulsed MFCs (particularly pressure pulsed MFCs). When the pulse supply period (pulse on period) ends, the shutoff valve on the downstream side is immediately closed and the output flow drops to zero. The pulse gas supply amount Δn (mol) used in the apparatus of FIG. 6 can be obtained by the formula 1 shown again below.

Wherein, Q _m is the pressure P _d, the gas temperature T and molecular weight MW and the specific heat ratio characteristics of the gas such as γ of the gas pressure P _u and the downstream side of the upstream side with respect to flow rates (system fluid measured by the flow sensor V _{d 2} is the dead volume between the control fluid and the shutoff valve, P _d is the measurement result of the downstream pressure, t ₁ is the start time of the pulse, and t ₂ is the pulse start time. The end time.

The following terms, including the dead volume V _d2 and the downstream P _d , are based on the law of conservation of mass.

This term is included in Equation 1 to compensate for the fluid present in the space between the control fluid and the shutoff valve. This term can be defined as the residual flow rate. The flow sensor may generate a flow signal after the shutoff valve is closed if there is a pressure difference between the upstream pressure sensor and the downstream pressure sensor in the flow channel. Since the shutoff valve is closed, this flow does not go to the processing room. However, fluid remains in the channel and the term in Equation 1 is intended to compensate for this.

During operation, the user can specify the following parameters for the molar-based pulse supply: (1) molar supply setpoint (n _sp ), (2) _{desired pulse-on period (Ton} ) (eg, target). ), (3) the sum of the pulse-on period and the pulse-off period (Τ _total ), and (4) the number of pulses (N). This information can be transmitted to the MFC 610 via the host controller 620. Based on this information, the controller 605 of the MFC 610 automatically adjusts the flow setting point and optionally the pulse-on period based on the flow rate measured by the flow sensor (eg, flow sensor 625) according to Equation 1. It is configured to supply exactly the desired number of moles of gas within the desired pulse-on period.

The MFC610 uses a molar-based pulse supply to control the flow setting point of the control valve 680 and optionally the actual pulse-on period, and adjust as necessary to reduce the number of moles supplied by each pulse. Control. Based on these parameters, the MFC 610 automatically supplies a flow of N consecutive pulses at the correct timing, with each pulse having a molar amount of Δn during each portion of the total pulse period during which MFC is on. For the rest of the total pulse-on and pulse-off periods ( _Total ), the MFC is turned off and the shutoff valve is closed. During the pulse supply, MFC610, in order to accurately provide the desired number of moles in the target pulse-on period (T _on) in for each pulse, based on the estimated number of moles of feedback provided during the pulse, The flow setting point (Q _sp ) of the control valve 680 is automatically adjusted. The MFC 610 may also adjust the flow setting point of the control valve 680 and optionally the actual pulse-on period based on the feedback of the previous pulse supply.

In certain situations (eg, during process startup after the system has been idle for some time), the demand for molar supply may be less than the mass of fluid in the volume of the flow channel. This is also called the "first wafer" problem. For example, the control valve may have a leak, which will result in increased pressure in the flow channel. This pressure may be sufficient to obtain the number of moles required for the pulse. In such a situation, the MFC may open only the shutoff valve without opening the control valve to supply a pulse of the desired fluid. During the pulse, the downstream pressure P _d is measured, and when the desired number of moles of fluid calculated from Equation 1 is obtained, the pulse can be terminated.

As is known in the art, the flow (Q) passing through the control fluid of the channel is the pressures ( _Pu and P _d ) on the upstream and downstream sides of the control fluid (ie, in the immediate vicinity of the control fluid). It can be expressed as a function of the characteristics of the gas such as pressure), the cross-sectional area (A) of the flow path passing through the control fluid, and the specific heat ratio γ and the molecular weight MW as shown in the following equation.

The function f _Q can be obtained by experimental data or experiments. When a flow nozzle is used as the control fluid, the following equation can be used.

In the equation, C is the discharge coefficient of the control fluid, R is the general gas constant, and T is the temperature of the gas.

Corresponding equations for other control fluids and mass flows passing through these control fluids can also be used and are known in the art.

A particular advantage obtained by embodiments of the present invention over conventional methods is improved accuracy of gas pulse delivery; by eliminating long pulse tails, it fits the required pulse shape; (especially for short periods of time). (About the pulse of) The supply speed has improved. From FIGS. 7A and 7B, it is possible to compare the pulse gas supply performance between the case where the integrated downstream shutoff valve is provided and the case where the integrated downstream shutoff valve is not provided.

As described above, FIG. 7A is a graph showing the pulse shape obtained using a system such as the system 500 of FIG. 5 which does not have an integrated shutoff valve. FIG. 7B is a graph showing the pulse shape obtained using a system with an integrated fast responsive shutoff valve such as the system 600 of FIG. Similar to FIG. 7A, FIG. 7B shows two curves, the ideal pulse shape 706 has a pulse width of 300 ms, and the actual pulse shape 708 was obtained using the system 600. Comparing the actual pulse shapes of FIGS. 7A and 7B, it is shown that the pulse shape of FIG. 7B is adapted to the ideal pulse shape by improving the accuracy of the gas pulse supply and eliminating the long pulse tail. .. It is possible to improve the supply speed by eliminating the pulse tail.

For pulsed MFCs with one or more external shutoff valves (FIGS. 8-10), these pulsed MFCs also directly control the downstream shutoff valve based on the pulse supply request. When a discharge line as shown in FIGS. 9 and 10 is adopted, the pulse MFC will connect the pulse MFC to the downstream shutoff valve at the end of the pulse supply and before the start of a new pulse supply. The residual gas captured in the meantime can be quickly discharged.

FIG. 8 shows an example of a pulse supply system 800 including a pulse MFC810 with an external shutoff valve 890. The pulse MFC 810 controls the gas flow from the gas source and the opening and closing of the shutoff valve 890 based on the pulse supply request received from the host controller 820.

FIG. 9 shows an example of a pulse supply system 900 including a pulse MFC 910 with an external three-way shutoff valve 930 and a discharge line. The shutoff valve 930, unlike the three-way shutoff valve 130 of FIG. 1, is directly controlled by the pulse MFC 910, not by the host controller 920.

An improved pulse MFC (such as MFC610) is retrofitted to an existing system with an external shutoff valve as shown in FIG. 1 to control the shutoff valve and using the method described herein. It is possible to provide an improved pulse supply. The improved pulsed MFC not only controls the flow over time like a standard MFC, but also compensates for the mass of fluid supplied during the pulse at the molar level. The host controller specifies the number of moles to be fed per pulse, in addition to other desired process parameters. However, this MFC controls the pulse supply cycle locally. In this case, the control and shutoff valves are controlled not based solely on time, but on the calculation of the estimated number of moles supplied. In order to terminate the pulse, it is necessary to calculate the estimated number of moles supplied quickly enough and to close the shutoff valve sufficiently quickly by the control signal. That is, this calculation is done locally in MFC.

FIG. 10 shows an example of a pulse supply system 1000 having a pulse MFC 1010, two external shutoff valves 1090, 1092, and a discharge line. These two shutoff valves 1090 and 1092 are controlled by the pulse MFC 1010 in response to a pulse supply request. As shown, the shutoff valve 1090 is configured to open and close the flow to the processing chamber, and the shutoff valve 1092 is configured to open and close the flow to the discharge line. The pulse supply request is transmitted to the MFC 1010 by the host controller 1020.

All patents, public relations and literature references cited herein are hereby incorporated by reference as part of this application.

Although the exemplary embodiments have been specifically illustrated and described above, one of ordinary skill in the art will make various modifications to the embodiments and details without departing from the scope of the embodiments included in the appended claims. It should be understood that

として決定するように構成されており、
式中、Ｖ _ｄ２ は前記制流体と前記遮断弁との間の前記デッドボリュームであり、Ｐ _ｄ は前記下流側圧力であるシステム。
［態様８］
態様６または７に記載のシステムにおいて、前記コントローラが、前記供給される流体の推定モル数を、下記式により決定するように構成されており、

式中、Δｎは前記推定モル数であり、Ｑ _ｍ は前記フローセンサにより計測された前記流量であり、Ｖ _ｄ２ は前記制流体と前記遮断弁との間の前記デッドボリュームであり、Ｐ _ｄ は前記下流側圧力であり、ｔ _１ は前記パルスの前記開始時間であり、ｔ _２ は前記パルスの前記終了時間であるシステム。
［態様９］
態様５から８のいずれか一態様に記載のシステムにおいて、前記流量が、前記上流側圧力、前記下流側圧力、および前記流体の１つ以上の特性の関数として計測されるシステム。
［態様１０］
態様９に記載のシステムにおいて、前記流体の前記１つ以上の特性には、分子量ＭＷおよび比熱比γが含まれるシステム。
［態様１１］
態様９に記載のシステムにおいて、前記フローチャネルにおける前記流体の温度を計測するように構成された温度センサをさらに備え、前記流量が、さらに、前記流体の前記温度の関数として計測されるシステム。
［態様１２］
態様１から１１のいずれか一態様に記載のシステムにおいて、前記コントローラが、ホストコントローラからの制御信号を受信するように構成され、前記制御信号が、前記流体の識別、前記流体のパルスの所望のモル数、および前記流体のパルスの継続時間を含むシステム。
［態様１３］
態様１に記載のシステムにおいて、前記遮断弁が、前記パルスＭＦＣに一体化されているシステム。
［態様１４］
態様１に記載のシステムにおいて、前記遮断弁が、前記パルスＭＦＣの外部に設けられているシステム。
［態様１５］
態様１４に記載のシステムにおいて、前記遮断弁が、処理室および排出ラインに接続された三方弁であるシステム。
［態様１６］
態様１５に記載のシステムにおいて、前記システムが複数の遮断弁を備え、前記遮断弁の１つが処理室に接続され、前記遮断弁の他の１つが排出ラインに接続されているシステム。
［態様１７］
流体のパルスを供給する方法であって、
制御弁を用いてフローチャネルへの流体のフローを制御することと、
フローセンサを用いて前記フローチャネルにおける流量を計測することと、
遮断弁の切替えを制御して、前記フローチャネルからの流体のパルスの開始および終了を行うことと、
前記制御弁を通過する流体のフローおよび前記遮断弁の切替えを制御して、前記流体のパルスの間に供給される流体の質量を制御することとを含む方法。
［態様１８］
態様１７に記載の方法において、前記制御弁を通過する前記流体のフローの制御が、前記遮断弁により開始および終了される前記パルスの間、前記フローセンサからのフィードバックに基づいて行われる方法。
［態様１９］
態様１７または１８に記載の方法において、
前記フローチャネル内において、前記制御弁および前記遮断弁の間に配置された制流体と前記制御弁との間の上流位置における上流側圧力を検出することと、
前記フローチャネル内において、前記制流体と前記遮断弁との間の下流位置における下流側圧力を検出することとをさらに含み、
前記フローチャネルにおける流量の計測が、前記上流側圧力および前記下流側圧力に基づいて行われる方法。
［態様２０］
態様１９に記載の方法において、ｉ）計測された前記流量、ｉｉ）計測された前記圧力、ｉｉｉ）前記流体のパルスの開始時間、およびｉｖ）前記流体のパルスの終了時間の関数として、供給される流体の推定モル数を決定することをさらに含み、
前記制御弁を通過する前記流体のフローおよび前記遮断弁の前記切替えが、前記供給される流体の推定モル数に基づいて制御される方法。
［態様２１］
態様２０に記載の方法において、ｉ）前記下流側圧力およびｉｉ）前記制流体と前記遮断弁との間の前記デッドボリュームの関数として残存流量を決定することをさらに含み、
前記供給される流体の推定モル数が、前記残存流量および計測された流量に基づいて決定される方法。 Although the exemplary embodiments have been specifically illustrated and described above, one of ordinary skill in the art will make various modifications to the embodiments and details without departing from the scope of the embodiments included in the appended claims. It should be understood that
In addition, the present invention includes the following contents as an embodiment.
[Aspect 1]
A fluid control system used to supply fluid pulses.
Flow channel and
A shutoff valve that starts and ends the pulse of fluid from the flow channel,
Equipped with a mass flow controller (MFC)
The mass flow controller
A control valve that controls the flow of fluid in the flow channel,
A flow sensor that measures the flow rate in the flow channel and
A system including a controller that controls the flow of a fluid passing through the control valve and the switching of the shutoff valve to control the mass of the fluid supplied during the pulse of the fluid.
[Aspect 2]
In the system according to aspect 1, the controller controls the flow of the fluid through the control valve based on feedback from the flow sensor during the pulses started and terminated by the shutoff valve. ..
[Aspect 3]
In the system according to aspect 1 or 2, the flow sensor
In the flow channel, the control fluid arranged between the control valve and the shutoff valve,
An upstream pressure sensor configured to detect an upstream pressure at an upstream position between the control valve and the control fluid in the flow channel.
A downstream pressure sensor configured to detect a downstream pressure at a downstream position between the control fluid and the shutoff valve in the flow channel.
A system in which the flow sensor measures a flow rate based on the upstream pressure and the downstream pressure.
[Aspect 4]
In the system according to aspect 3, the controller is configured to close the shutoff valve based on a calculation of the mass of the fluid supplied during the pulse of the fluid.
[Aspect 5]
In the system according to aspect 3 or 4, the controller i) measured the flow rate, ii) the detected pressure, iii) the start time of the fluid pulse, and iv) the end time of the fluid pulse. As a function of, it is configured to determine the estimated number of moles of fluid supplied,
A system in which the controller is configured to control the flow through the control valve and the switching of the shutoff valve based on an estimated number of moles of the supplied fluid.
[Aspect 6]
In the system according to aspect 5, the controller is configured to determine the estimated number of moles of the supplied fluid based on the determination of the residual flow rate and the measured flow rate.
[Aspect 7]
In the system according to aspect 6, the controller receives the upstream pressure signal corresponding to the upstream pressure and the downstream pressure signal corresponding to the downstream pressure, i) the downstream pressure and ii). The residual flow rate is defined as a function of the dead volume between the control fluid and the shutoff valve.

Is configured to determine as
In the equation, V _d2 is the dead volume between the control fluid and the shutoff valve, and P _d is the downstream pressure.
[Aspect 8]
In the system according to aspect 6 or 7, the controller is configured to determine the estimated number of moles of the supplied fluid by the following equation.

In the equation, Δn is the estimated number of moles, Q _m is the flow rate measured by the flow sensor, V _d2 is the dead volume between the control fluid and the shutoff valve, and P _d is. A system in which the downstream pressure, t ₁ is the start time of the pulse, and t ₂ is the end time of the pulse.
[Aspect 9]
In the system according to any one of aspects 5 to 8, the flow rate is measured as a function of one or more properties of the upstream pressure, the downstream pressure, and the fluid.
[Aspect 10]
In the system according to aspect 9, the system in which the one or more properties of the fluid include a molecular weight MW and a specific heat ratio γ.
[Aspect 11]
The system according to aspect 9, further comprising a temperature sensor configured to measure the temperature of the fluid in the flow channel, the flow rate is further measured as a function of the temperature of the fluid.
[Aspect 12]
In the system according to any one of aspects 1 to 11, the controller is configured to receive a control signal from the host controller, which is the desired fluid identification, pulse of the fluid. A system that includes the number of moles and the duration of a pulse of said fluid.
[Aspect 13]
In the system according to aspect 1, the shutoff valve is integrated with the pulse MFC.
[Aspect 14]
In the system according to the first aspect, the shutoff valve is provided outside the pulse MFC.
[Aspect 15]
In the system according to aspect 14, the shutoff valve is a three-way valve connected to a processing chamber and a discharge line.
[Aspect 16]
In the system according to aspect 15, the system includes a plurality of shutoff valves, one of which is connected to a processing chamber and the other of which is connected to a discharge line.
[Aspect 17]
It is a method of supplying a pulse of fluid,
Controlling the flow of fluid to the flow channel using a control valve
Measuring the flow rate in the flow channel using a flow sensor,
Controlling the switching of the shutoff valve to start and stop the pulse of the fluid from the flow channel,
A method comprising controlling the flow of a fluid passing through the control valve and switching of the shutoff valve to control the mass of the fluid supplied during the pulse of the fluid.
[Aspect 18]
A method according to aspect 17, wherein the control of the flow of the fluid through the control valve is performed based on feedback from the flow sensor during the pulses started and terminated by the shutoff valve.
[Aspect 19]
In the method according to aspect 17 or 18.
In the flow channel, detecting the upstream pressure at the upstream position between the control fluid arranged between the control valve and the shutoff valve and the control valve, and
Further including detecting downstream pressure at a downstream position between the control fluid and the shutoff valve in the flow channel.
A method in which the flow rate in the flow channel is measured based on the upstream pressure and the downstream pressure.
[Aspect 20]
In the method according to aspect 19, i) the measured flow rate, ii) the measured pressure, iii) the start time of the pulse of the fluid, and iv) the end time of the pulse of the fluid are supplied as a function. Further includes determining the estimated number of moles of fluid
A method in which the flow of the fluid passing through the control valve and the switching of the shutoff valve are controlled based on the estimated number of moles of the supplied fluid.
[Aspect 21]
The method of aspect 20 further comprises determining the residual flow rate as a function of i) the downstream pressure and ii) the dead volume between the control fluid and the shutoff valve.
A method in which the estimated number of moles of the supplied fluid is determined based on the residual flow rate and the measured flow rate.

Claims (21)

A fluid control system used to supply fluid pulses.
Flow channel and
A shutoff valve that starts and ends the pulse of fluid from the flow channel,
Equipped with a mass flow controller (MFC)
The mass flow controller
A control valve that controls the flow of fluid in the flow channel,
A flow sensor that measures the flow rate in the flow channel and
A system including a controller that controls the flow of a fluid passing through the control valve and the switching of the shutoff valve to control the mass of the fluid supplied during the pulse of the fluid. In the system of claim 1, the controller controls the flow of the fluid through the control valve, based on feedback from the flow sensor, during the pulses started and terminated by the shutoff valve. system. In the system according to claim 1 or 2, the flow sensor
In the flow channel, the control fluid arranged between the control valve and the shutoff valve,
An upstream pressure sensor configured to detect an upstream pressure at an upstream position between the control valve and the control fluid in the flow channel.
A downstream pressure sensor configured to detect a downstream pressure at a downstream position between the control fluid and the shutoff valve in the flow channel.
A system in which the flow sensor measures a flow rate based on the upstream pressure and the downstream pressure. In the system of claim 3, the controller is configured to close the shutoff valve based on a calculation of the mass of the fluid supplied during the pulse of the fluid. In the system of claim 3 or 4, the controller i) measures the flow rate, ii) the detected pressure, iii) the start time of the fluid pulse, and iv) the end of the fluid pulse. As a function of time, it is configured to determine the estimated number of moles of fluid supplied,
A system in which the controller is configured to control the flow through the control valve and the switching of the shutoff valve based on an estimated number of moles of the supplied fluid. In the system of claim 5, the controller is configured to determine the estimated number of moles of the supplied fluid based on the determination of the residual flow rate and the measured flow rate. In the system according to claim 6, the controller receives an upstream pressure signal corresponding to the upstream pressure and a downstream pressure signal corresponding to the downstream pressure, and i) the downstream pressure and ii. ) The residual flow rate as a function of the dead volume between the control fluid and the shutoff valve.

Is configured to determine as
In the equation, V _d2 is the dead volume between the control fluid and the shutoff valve, and P _d is the downstream pressure. In the system according to claim 6 or 7, the controller is configured to determine the estimated number of moles of the supplied fluid by the following equation.

In the equation, Δn is the estimated number of moles, Q _m is the flow rate measured by the flow sensor, V _d2 is the dead volume between the control fluid and the shutoff valve, and P _d is. A system in which the downstream pressure, t ₁ is the start time of the pulse, and t ₂ is the end time of the pulse. In the system according to any one of claims 5 to 8, the flow rate is measured as a function of one or more properties of the upstream pressure, the downstream pressure, and the fluid. The system according to claim 9, wherein the one or more properties of the fluid include a molecular weight MW and a specific heat ratio γ. The system according to claim 9, further comprising a temperature sensor configured to measure the temperature of the fluid in the flow channel, the flow rate is further measured as a function of the temperature of the fluid. In the system according to any one of claims 1 to 11, the controller is configured to receive a control signal from a host controller, the control signal being the identification of the fluid, the desire for a pulse of the fluid. A system that includes the number of moles of the fluid and the duration of the pulse of the fluid. In the system according to claim 1, the shutoff valve is integrated with the pulse MFC. In the system according to claim 1, the shutoff valve is provided outside the pulse MFC. In the system according to claim 14, the shutoff valve is a three-way valve connected to a processing chamber and a discharge line. In the system according to claim 15, the system includes a plurality of shutoff valves, one of which is connected to a processing chamber and the other of which is connected to a discharge line. It is a method of supplying a pulse of fluid,
Controlling the flow of fluid to the flow channel using a control valve
Measuring the flow rate in the flow channel using a flow sensor,
Controlling the switching of the shutoff valve to start and stop the pulse of the fluid from the flow channel,
A method comprising controlling the flow of a fluid passing through the control valve and switching of the shutoff valve to control the mass of the fluid supplied during the pulse of the fluid. The method according to claim 17, wherein the control of the flow of the fluid passing through the control valve is performed based on the feedback from the flow sensor during the pulse started and ended by the shutoff valve. In the method according to claim 17 or 18.
In the flow channel, detecting the upstream pressure at the upstream position between the control fluid arranged between the control valve and the shutoff valve and the control valve, and
Further including detecting downstream pressure at a downstream position between the control fluid and the shutoff valve in the flow channel.
A method in which the flow rate in the flow channel is measured based on the upstream pressure and the downstream pressure. In the method of claim 19, i) the measured flow rate, ii) the measured pressure, iii) the start time of the fluid pulse, and iv) the supply as a function of the end time of the fluid pulse. Further including determining the estimated number of moles of fluid to be
A method in which the flow of the fluid passing through the control valve and the switching of the shutoff valve are controlled based on the estimated number of moles of the supplied fluid. The method of claim 20 further comprises determining the residual flow rate as a function of i) the downstream pressure and ii) the dead volume between the control fluid and the shutoff valve.
A method in which the estimated number of moles of the supplied fluid is determined based on the residual flow rate and the measured flow rate.

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